Promoting the best individual contributor to the role of manager doesn't often work well and not because the person isn't capable. It's actually because of two very specific reasons:
There is too much emphasis placed on technical rather than people and organizational competence, and
Most organizations don't have a strong enough leadership and management development culture and structure.
Most organizations place much more emphasis on technical versus people and organizational competence. You can see it clearly in the policies, procedures and people related systems like hiring, reviews etc. People skills are regularly referred to as "soft" and "squishy" but no one denies the power of them. The reason they don't get as much credit or focus is mostly because because they're hard to measure, manage and develop. And what happens is that the newly promoted manager leans way too much on their technical competence in trying to lead a team and either does everything themselves or demoralizes their team by unintentionally (or sometimes intentionally) making their team feel incompetent if they don't do things the way the boss does.
Google actually figured this out the hard way.
Everyone knows Google the search function and the company but few know about the fascinating and really game changing experiment they went through, not involving technology, but management and their people called Project Oxygen. Basically, back in 2002, they eliminated managers. That's right, no managers anywhere at all. They thought managers were about control and if they had the best and brightest people in the world working for them, why did they need such control functions like managers? They quickly abandoned that experiment after the senior leadership team was bombarded with requests for support, guidance and approval. They learned managers are critical, brought them back and then set out to understand why.
Google discovered the qualities that made the best managers so great and have developed people systems to support those qualities. Guess what those qualities relate to? That's right, people. Here they are straight from Google's site outlining all of their people and organizational studies called re:work:
And by the way, these are in order of importance. Where does technical competence land on this list? Dead last! Still important, but not the most important. So then why is this the single greatest factor in decisions related to promotion to management in the vast majority of organizations? The answer: "because that's they way its always been done" said the the leaders of stagnant, stale or otherwise no longer existing companies.
People today are rightfully demanding better leadership. Its shows in the engagement of the workforce and in their willingness to jump ship.
So Then What?
If organizations are going to better reach their potential and thrive versus survive then people and organizational skills have to be better developed and prioritized. There are 3 basic but comprehensive steps to the process:
Define leadership effectiveness for your organization. And it should mostly have to do with people just like Google's list, but doesn't have to be exactly the same, nor should it. Just putting it in writing and your organization's own words is incrediby powerful. Then and organization should
Develop internal and external courses, programs and development opportunities designed around those competencies.
Finally, build those leadership competencies into all of the people systems like hiring, onboarding, performance reviews and firing help to regularly reinforce those competencies in to managers at all levels.
Once these steps are started, any organization is well on its well to fulfilling its full potential and making a real impact on its people, customers and it's part of the world.